This invention relates to an electronic musical instrument and, more particularly, to a key scaling technique controlling a waveshape of a generating tone in accordance with the tone pitch of the tone or a tone range to which the tone belongs.
Known in the art is a technique as disclosed in the specification of U.S. Pat. No. 4,437,379 in which two kinds of waveshapes for a high frequency tone range and a low frequency tone range are respectively prepared and a waveshape of an intermediate tone range therebetween is produced through interpolation between the two kinds of waveshapes by the use of a scaling (weighting) coefficient corresponding to the tone pitch (tone range) of the tone to be generated. In the prior art technique, the waveshapes used for scaling are fixed to the two kinds of tone ranges, i.e., those for the high frequency tone range and the low frequency tone range resulting in an inadequate key scaling control. In some tone colors to be realized, it is desirable that scaling characteristics of several kinds should be provided for corresponding tone ranges. Such control, however, has not been feasible at all in the prior art technique.
On the other hand, there are some tone colors that do not require key scaling. In those tone colors, tone generation and control circuits of plural channels provided for key scaling are wasted.
It is, therefore, an object of the present invention to provide an electronic musical instrument capable of controlling modes of key scaling characteristic of a tone waveshape in various manners thereby to obtain a tone of a good quality whose tone waveshape changes in accordance with the tone pitch or tone range.
It is another object of the invention to provide an electronic musical instrument capable of utilizing tone generation and control circuits without waste and synthesizing a tone in a manner suited for the tone color to be generated. More specifically, there is provided an electronic musical instrument capable of selectively effecting, depending upon a tone color to be produced, synthesis of a tone of a desired characteristic by key scaling a tone waveshape in accordance with the tone pitch (tone range) of the tone to be generated or synthesis of a tone of a desired characteristic by combining tones of plural tone generation systems imparted with different envelopes.
It is still another object of the invention to provide an electronic musical instrument in which plural systems for controlling a tone waveshape by the key scaling technique are provided to realize a control which is even richer in variety.